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Fetal growth dependent on race, ethnicity of mother

Fetuses of minority mothers may be misclassified as growth-restricted based on current standards of fetal development, according to recently published data.

Germaine Buck Louise, PhD, director of the Division of Intramural Population Health Research for the NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, and colleagues analyzed sonograms of 1,737 women with low-risk pregnancies across 12 hospitals to assess trends in fetal growth among different races and ethnicities. The women underwent five sonograms between their 16^th and 41^st weeks of pregnancy.

Among participants, 26% were non-Hispanic white, 26% were non-Hispanic black, 28% were Hispanic and 20% were Asian. All women were aged 18 to 40 years.

Significant disparities in estimated fetal weight after 20 weeks gestation were seen between races.

At 39 weeks gestation, the largest fetuses were among white mothers, with a 95^th percentile of 4,402 g, while the smallest were among black mothers, with a 95^th percentile of 4,053 g, according to the study. The 95^th percentiles for Hispanic and Asian fetuses at 39 weeks were 4,226 g and 4,078 g, respectively.

When comparing fetus growth with the current weight standards, which were mainly derived from pregnancies of white, middle-class women, according to a press release, approximately 15% of fetuses of minority women were misclassified as growth restricted.

“Doctors like to be proactive — if they suspect there’s a problem with a fetus’ growth, then they’re likely to order tests and investigate. But inaccurate standards may be leading women to receive unnecessary tests — not to mention the stress of thinking something may be wrong — when their pregnancies actually are on track,” Buck Louis said in a press release.

Buck Louis and colleagues noted that developing fetal growth standards specific to races and ethnicities are necessary to avoid fetus misclassification. Additionally, future research should study whether country or region affect fetal growth, according to the researchers. – by Casey Hower

Disclosures: The researchers report no relevant financial disclosures.